AutoIt WinExists Function

If you got multiple windows, it can be more secure to perform the check using a window handle, rather than checking directly.

Normally you likely won't need to check for the existence of a window, but it can be a good idea, if there's a possibility that the window has been closed, by someone who is using the computer – either on purpose or by accident. Otherwise your script could, for example, start clicking unintended places.